Time delay device



June 14, 1938. G. LOWKRANTZ' 2,120,787

TIME DELAY DEVICE Filed Dec. 1, 1936 f L 50 g 7 f INVENTOR.

m BY

' A TTORNEY Patented June 14, 1938 UNITED STATES PATENT OFFICE TIME DELAY DEVICE Application December 1, 1936, Serial No. 113,620

9 Claims.

This invention relates to time delay mechanisms and more particularly to mechanisms adapted to delay the applicationof a connected load to a supply circuit whereby the supply circuit may be conditioned properly during the delayed time interval and then automatically connected to the applied load.

A specific application of the present invention is in connection with various electric discharge devices such as thermionic tubes. In order to secure long tube life it is desirable to delay the application of any load thereto until sufficient time has elapsed for the cathodes to become completely heated after the supply source has been connected thereto.

An object of the present invention is to pro- Vide means whereby the load circuit is connected to the supply source or circuit after a predetermined timed interval has elapsed after the controlling element has been operated.

Another object of the invention is the provision of means whereby the time delay mechanism becomes effective if any interruption in the supply power occurs during the initial said predetermined timed interval or at any time thereafter.

Various other objects and advantages of the invention will be obvious from the following particular description of one form of mechanism embodying the invention or from an inspection of the accompanying drawing; and the invention also constitutes certain new and useful features of construction and combination of parts hereinafter set forth and claimed.

In the accompanying drawing, a circuit diagram is shown of the invention showing diagrammatically the control elements thereof.

Referring to the drawing, a full wave rectiher I is shown representing one type of power supply unit, the anodes of which are connected in the usual manner to the terminals of the secondary winding 2 of transformer 3, the center tap of said winding connected to one side of the coil of clutch magnet 4 and the other side of is attached to or may be an integral part of the cam 13 which are rotatably mounted on shaft 8. A support member I4 is shown for shaft 8 and upon which is attached a stop finger l5 to engage a stop IS on the cam so as to prevent the cam to be returned farther by spring ll when the clutch members are disengaged. Cooperating with cam I3 is a cam follower I8 mounted on the arm 19 which is an extension of spring blade 20. The multi-contact switch 2| comprises a plurality of normally open contacts 22, 23, and 24 and a normally closed contact 25. The contacts are so adjusted that as the cam. I3 is rotated and due to its configuration actuates the spring blade to the right, the contacts are adapted to be operated in the following order; first contact 22 closes followed in succession by the closure of contacts 23 and then contacts 24; finally, when the said contacts are closed, contacts 25 are opened.

The operation of the mechanism is as follows: Upon closure of the main switch the secondary Winding 2 and 5 of transformer 3 are energized. The clutch magnet 4 connected directly to winding 2 is energized to attract its armature l l causing the clutch members It and IE to be engaged. Through the normally closed contacts 25, conductor 21, speed control resistor 28, or like device, the motor 9 is energized rotating shaft 8 and the cam 18 through clutch members It and i2 which are now engaged. The tube cathode starts to heat at the same time the clutch magnet and motor are energized. It will be noted at this time that the load 1 is disconnected from the output of the tube 1 by means of the normally open contacts 22, .23, and 24. The cathode continues to be energized and heated for a predetermined time interval equivalent to the time necessary for the cathode to attain its proper operating temperature before the high section or lobe of the cam 13 approaches the cam roller or follower I8. As the cam is rotated at a predetermined rate and in accordance with the elapsed time required, the spring blade 2|] will gradually be positioned so that contacts 22 are closed. By this time the cathode is completely heated and the tube passes current which flows from the cathode through filter condenser 30, resistor 3|, and contacts 22 to the center tap of winding 2.

The said resistor limits the initial charging current of the condenser and as the condenser is gradually charged to nearly full voltage, the spring blade 20 is positioned to close contacts 23 which causes the resistance 3| to be shunted from the described circuit and thereby the condenser 30 is connected directly across the rectiiier output to be fully charged. Finally, contacts 24 are closed to connect the external load 1 directly to the center tap of winding 2 thereby connecting the load directly to the power supply therefor. After connecting the load to the rectifier tube the normally closed contacts 25 in the motor circuit are opened to cause the motor to be deenergized. The cam i3 remains in its final position to maintain the said contacts in an operated position so long as the clutch magnet 4 remains energized so that the clutch members I0 and I 2 remain engaged. If, however, there is an interruption in the supply voltage at any time, due to power failure or opening of the switch 26, etc., the clutch magnet 4 is deenergized to release its armature and disengage the said clutch members, whereupon the spring I! will return the cam. 53 to the normal starting position and is prevented from being returned to any other position by means of stops it and i5. In this manner, the cathode will always have sulficient time to regain the proper operating temperature before the load is again applied to the tube.

While there has been shown and described and pointed out the fundamental novel features of the invention as applied to a single modification, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention therefore to be limited only as indicated by the scope of the following claims.

What is claimed is as follows:

1. A device of the character described comprising, in combination, a thermionic tube comprising cathode and anode elements and circuits therefor, means to energize the cathode circuit, a load circuit, control means comprising cam operated contacts, and means to operate said contacts after energization of the said cathode circuit for a predetermined timed interval thereby connecting the said load circuit to the anode circuit.

2. A device of the character described comprising, in combination, a. thermionic tube comprising cathode and anode elements and circuits therefor, a supply source to energize the said circuits, a load circuit, control means comprising cam operated contacts, means to operate said contacts after energization of the said cathode circuit for a predetermined timed interval thereby connecting the said load circuit to the anode circuit, and means to maintain the said contacts operated during the time the supply source is effective to energize the said circuits.

3. A device of the character described comprising, in combination, a cam element and supporting means therefor, means to rotate the supporting means continuously, means to connect the cam element and the said supporting means thereby rotating the cam element from a normal starting position, contacts: operated by said cam element, and means to prevent further rotation of said cam element thereby maintaining the said contacts operated.

4. The invention set forth in claim 3 provided with means to return the cam element to the normal starting position.

5. A device of the character described comprising, in combination, a thermionic tube com prising cathode and anode elements and circuits therefor, a supply source to energize the said circuits, a load circuit, a cam and rotating means therefor, control means energized by said supply source to operate the cam rotating means, contacts cooperating with said cam and operated a predetermined timed interval after energization of the said control means to connect the load circuit to the anode circuit, and means to prevent further rotation of said cam thereby maintaining the said cam contacts operated.

6. A device of the character described comprising, in combination, a thermionic tube comprising cathode and anode elements and circuits therefor, a supply source to energize the said circuits, a load circuit, a cam normally positioned in an initial starting position and rotating means therefor, control means energized by said supply source to operate the ca). rotating means, a plurality of contacts cooperating with said cam and operated a predetermined timed interval after energization of the said control means to connect the load circuit to the anode circuit, means to prevent further rotation of said cam thereby maintaining all the said cam operated contacts in operative position, and means upon discontinuance of the supply source and decnergization of said control means to return the said cam to said initial starting position.

7. The invention set forth in claim 6 in which the cam configuration is such as to operate the said contacts progressively.

8. A device of the character described comprising, in combination, a rectifier tube comprising cathode and anode elements and circuits therefor, a supply source to energize the said circuits, a load circuit, control means, a 0011- denser, and means including time delay means to operate the said control means a predetermined timed interval after energization of the cathode circuit to first connect the condenser to said anode circuit and then connect the load circuit to said anode circuit including the condenser.

9. A device of the character described comprising, in combination, a rectifier tube comprising cathode and anode elements and circuits therefor, a supply source to energize the said circuits, a load circuit, control means, a condenser and a charging resistor therefor, and means including time delay means to operate the said control means a predetermined timed interval after energization of the cathode circuit to connect first the condenser and resistor to the anode circuit, then shunting said resistor from the anode circuit and then connecting the load circuit to said anode circuit including the condenser.

GUNNE LOWKRANTZ. 

